The electric-current stabilized semi-metallic state in the quasi-two-dimensional Mott insulator Ca2RuO4 exhibits an exceptionally strong diamagnetism. Through a comprehensive study using neutron and X-ray diffraction, we show that this non-equilibrium phase assumes a crystal structure distinct from those of equilibrium metallic phases realized in the ruthenates by chemical doping, high pressure and epitaxial strain, which in turn leads to a distinct electronic band structure. Dynamical mean field theory calculations based on the crystallographically refined atomic coordinates and realistic Coulomb repulsion parameters indicate a semi-metallic state with partially gapped Fermi surface. Our neutron diffraction data show that the non-equilibrium behavior is homogeneous, with antiferromagnetic long-range order completely suppressed. These results provide a new basis for theoretical work on the origin of the unusual non-equilibrium diamagnetism in Ca2RuO4.
@article{arxiv.1806.06455,
title = {A Unique Crystal Structure of Ca$_2$RuO$_4$ in the Current Stabilized Semi-Metallic State},
author = {J. Bertinshaw and N. Gurung and P. Jorba and H. Liu and M. Schmid and D. T. Mantadakis and M. Daghofer and M. Krautloher and A. Jain and G. H. Ryu and O. Fabelo and P. Hansmann and G. Khaliullin and C. Pfleiderer and B. Keimer and B. J. Kim},
journal= {arXiv preprint arXiv:1806.06455},
year = {2019}
}